The purpose of this study was to investigate the variables that had an effect on the maturity of career attitude in middle school students. Independent variables were categorized into three groups: individual-related variables, family-related variables, and school-related variables. The individual-related variables were gender difference, academic year, academic achievement, and self-efficacy. The family-related variables were socio-economic status of the family, communication about career with parents, parental support, sibling's support, and value orientation of the family. The school-related variables included communication about career with friends, teacher's support, and friend's support. The subjects of this study were 490 students who were selected at random from first, second, and third grade of middle school in Daegu. A questionnaire was used for the survey. It consisted of a career attitude maturity scale, a self-efficacy scale, a communication scale, a value orientation of the family scale, and a social support scale. The data was analyzed by factor analysis, multiple regression analysis, and hierarchical regression analysis. The major findings of this study are summarized as follow: First, among the individual-related variables that had an effect on the maturity of career attitude in middle school students, self-efficacy affected all sub-factors of how mature they were in matters relating to career. Academic achievement affected decisiveness and preparation-- maturity of career attitude subfactors. And gender difference and academic year affected preparation and goal orientation. Second, the results of the family-related variables that had an effect on the maturity of career attitudes in middle school students were that communication about career with parents affected decisiveness, preparation, and confidence-- maturity of career attitude sub-factors, socio-economic status of the family and sibling's support affected confidence. And value orientation of the family affected goal orientation and independence. Third, the results of the school-related variables that had an effect on the maturity of career attitude in middle school students were that communication about career with friends affected preparation-- a maturity of career attitude sub-factor; teacher's support affected decisiveness, preparation, and confidence; and friend's support affected confidence and independence. Fourth, decisiveness, preparation, and confidence among the maturity of career attitude sub-factors were affected the most by individual variables. And self-efficacy was the most significant. Goal orientation and independence were affected the most by family-related variables.